Devices offering protection from over voltages are well known. For example, such MOSFET protection devices provide protection from surges on the main power supply line and on input/output signal lines.
In the event a voltage supply is lost, such as, for example causing a loss of bias, the protected device may still be subject to voltage surges. For example, where discrete MOSFET's are used to protect a device from over voltages, residual bias may leave the MOSFET gate fully charged causing the MOSFET to continue to function and subjecting the protected device to a voltage surge.